An antenna array (or array antenna) is a set of multiple radiating elements that work together as a single antenna to transmit or receive radio waves. The individual radiating elements (often referred to simply as “elements”) can be connected to a receiver and/or transmitter by circuitry that applies appropriate amplitude and/or phase adjustment of signals received and/or transmitted by the radiating elements. When used for transmitting, the radio waves radiated by each individual radiating element combine and superpose with each other, adding together (interfering constructively) to enhance the power radiated in desired directions, and cancelling (interfering destructively) to reduce the power radiated in other directions. Similarly, when used for receiving, the separate received signals from the individual radiating elements are combined with the appropriate amplitude and/or phase relationship to enhance signals received from the desired directions and cancel signals from undesired directions.
An antenna array can achieve an elevated gain (directivity) with a narrower beam of radio waves, than can be achieved by a single antenna. In general, the larger the number of individual antenna elements used, the higher the gain and the narrower the beam. Some antenna arrays (such as phased array radars) can be composed of thousands of individual antennas. Arrays can be used to achieve higher gain (which increases communication reliability), to cancel interference from specific directions, to steer the radio beam electronically to point in different directions and/or for radio direction finding.